Virus kills brain tumours

Researchers in the United States have successfully used a virus to kill brain tumours in mice, a finding which may hold out some hope for treatment of the most pervasive form of the cancer in humans.

A team at the Yale Medical School transplanted human brain tumours into the brains of mice, before injecting the mice with a lab-created virus called vesicular stomatitis virus, or VSV.

They found that the virus found its way into the brain and was able to kill the deadly tumours, while leaving normal cells unharmed.

The findings show that viruses may be a useful therapeutic tool against brain tumours, which kill more than 200,000 people in the US alone, and are currently incurable.

Yale neurosurgery professor Anthony von den Pol said the study could have important implications for possible human treatments down the line.

Yale medical school Dean Robert Alpern called the study 'groundbreaking', saying that it is currently expected that someone diagnosed with this condition will die. He said the study could pave the way for a non-toxic human treatment.

In the experiment on the mice, the tumour cells, which had been infected with the virus, were dying or dead within three days of the virus being injected. Normal brain cells had been spared, however.

But von den Pol called for further tests to establish non-toxicity further before the technology could go to human trials.

Existing treatment methods for brain tumors include chemotherapy, radiation and surgery, which work by slowing down the progress of a tumour but are typically unable to eliminate all tumour cells, and tumour growth begins again within days. Drugs are often prevented from reaching brain tumours by the blood-brain barrier.

Von den Pol said there was a possibility that the virus could infect one tumour cell and then create thousands of virus particles that then go on to infect other tumour cells, acting as a self-amplifying anti-cancer agent.

Co-author Guido Wollmann said scientists have been testing the technique of using viruses against cancers for several decades, but earlier experiments used viruses that only infected particular tumour cells.

Wollmann said this technique had failed to date, because brain tumours are composed of many different types of cells, which mutate rapidly, making it hard to target them.

He said his team had started with the aim of finding a virus with a much broader spectrum of infection.

What makes VSV special is that it is repelled by the defensive mechanisms of normal body cells, so it can be used to target tumour cells, which lack these defences.

Researchers are now working to eliminate the probability of the virus’ infecting non-tumor cells — a process that can be engineered by genetic mutations, additions and deletions — while still retaining its ability to infect viral cells.